test/c/std/lzw.c - third_party/wuffs - Git at Google

 // Copyright 2017 The Wuffs Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //    https://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 // ----------------

 /*
 This test program is typically run indirectly, by the "wuffs test" or "wuffs
 bench" commands. These commands take an optional "-mimic" flag to check that
 Wuffs' output mimics (i.e. exactly matches) other libraries' output, such as
 giflib for GIF, libpng for PNG, etc.

 To manually run this test:

 for CC in clang gcc; do
   $CC -std=c99 -Wall -Werror lzw.c && ./a.out
   rm -f a.out
 done

 Each edition should print "PASS", amongst other information, and exit(0).

 Add the "wuffs mimic cflags" (everything after the colon below) to the C
 compiler flags (after the .c file) to run the mimic tests.

 To manually run the benchmarks, replace "-Wall -Werror" with "-O3" and replace
 the first "./a.out" with "./a.out -bench". Combine these changes with the
 "wuffs mimic cflags" to run the mimic benchmarks.
 */

 // ¿ wuffs mimic cflags: -DWUFFS_MIMIC

 // Wuffs ships as a "single file C library" or "header file library" as per
 // https://github.com/nothings/stb/blob/master/docs/stb_howto.txt
 //
 // To use that single file as a "foo.c"-like implementation, instead of a
 // "foo.h"-like header, #define WUFFS_IMPLEMENTATION before #include'ing or
 // compiling it.
 #define WUFFS_IMPLEMENTATION

 // Defining the WUFFS_CONFIG__MODULE* macros are optional, but it lets users of
 // release/c/etc.c choose which parts of Wuffs to build. That file contains the
 // entire Wuffs standard library, implementing a variety of codecs and file
 // formats. Without this macro definition, an optimizing compiler or linker may
 // very well discard Wuffs code for unused codecs, but listing the Wuffs
 // modules we use makes that process explicit. Preprocessing means that such
 // code simply isn't compiled.
 #define WUFFS_CONFIG__MODULES
 #define WUFFS_CONFIG__MODULE__BASE
 #define WUFFS_CONFIG__MODULE__LZW

 // If building this program in an environment that doesn't easily accommodate
 // relative includes, you can use the script/inline-c-relative-includes.go
 // program to generate a stand-alone C file.
 #include "../../../release/c/wuffs-unsupported-snapshot.c"
 #include "../testlib/testlib.c"

 // ---------------- LZW Tests

 const char*  //
 test_wuffs_lzw_decode_interface() {
   CHECK_FOCUS(__func__);
   wuffs_lzw__decoder dec;
   CHECK_STATUS("initialize",
                wuffs_lzw__decoder__initialize(
                    &dec, sizeof dec, WUFFS_VERSION,
                    WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
   return do_test__wuffs_base__io_transformer(
       wuffs_lzw__decoder__upcast_as__wuffs_base__io_transformer(&dec),
       "test/data/bricks-nodither.indexes.giflzw", 1, SIZE_MAX, 19200, 0x4F);
 }

 const char*  //
 do_test_wuffs_lzw_decode(const char* src_filename,
                          uint64_t src_size,
                          const char* want_filename,
                          uint64_t want_size,
                          uint64_t wlimit,
                          uint64_t rlimit) {
   wuffs_base__io_buffer have = ((wuffs_base__io_buffer){
       .data = g_have_slice_u8,
   });
   wuffs_base__io_buffer want = ((wuffs_base__io_buffer){
       .data = g_want_slice_u8,
   });
   wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
       .data = g_src_slice_u8,
   });

   CHECK_STRING(read_file(&src, src_filename));
   if (src.meta.wi != src_size) {
     RETURN_FAIL("src size: have %d, want %d", (int)(src.meta.wi),
                 (int)(src_size));
   }
   // The first byte in that file, the LZW literal width, should be 0x08.
   uint8_t literal_width = src.data.ptr[0];
   if (literal_width != 0x08) {
     RETURN_FAIL("LZW literal width: have %d, want %d", (int)(src.data.ptr[0]),
                 0x08);
   }
   src.meta.ri++;

   CHECK_STRING(read_file(&want, want_filename));
   if (want.meta.wi != want_size) {
     RETURN_FAIL("want size: have %d, want %d", (int)(want.meta.wi),
                 (int)(want_size));
   }

   wuffs_lzw__decoder dec;
   CHECK_STATUS("initialize",
                wuffs_lzw__decoder__initialize(
                    &dec, sizeof dec, WUFFS_VERSION,
                    WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
   wuffs_lzw__decoder__set_literal_width(&dec, literal_width);
   int num_iters = 0;
   while (true) {
     num_iters++;
     wuffs_base__io_buffer limited_have = make_limited_writer(have, wlimit);
     wuffs_base__io_buffer limited_src = make_limited_reader(src, rlimit);
     size_t old_wi = have.meta.wi;
     size_t old_ri = src.meta.ri;

     wuffs_base__status status = wuffs_lzw__decoder__transform_io(
         &dec, &limited_have, &limited_src, g_work_slice_u8);
     have.meta.wi += limited_have.meta.wi;
     src.meta.ri += limited_src.meta.ri;
     if (wuffs_base__status__is_ok(&status)) {
       if (src.meta.ri != src.meta.wi) {
         RETURN_FAIL("transform_io returned \"ok\" but src was not exhausted");
       }
       break;
     }
     if ((status.repr != wuffs_base__suspension__short_read) &&
         (status.repr != wuffs_base__suspension__short_write)) {
       RETURN_FAIL("transform_io: have \"%s\", want \"%s\" or \"%s\"",
                   status.repr, wuffs_base__suspension__short_read,
                   wuffs_base__suspension__short_write);
     }

     if (have.meta.wi < old_wi) {
       RETURN_FAIL("write index have.wi went backwards");
     }
     if (src.meta.ri < old_ri) {
       RETURN_FAIL("read index src.ri went backwards");
     }
     if ((have.meta.wi == old_wi) && (src.meta.ri == old_ri)) {
       RETURN_FAIL("no progress was made");
     }
   }

   if ((wlimit < UINT64_MAX) || (rlimit < UINT64_MAX)) {
     if (num_iters <= 1) {
       RETURN_FAIL("num_iters: have %d, want > 1", num_iters);
     }
   } else {
     if (num_iters != 1) {
       RETURN_FAIL("num_iters: have %d, want 1", num_iters);
     }
   }

   return check_io_buffers_equal("", &have, &want);
 }

 const char*  //
 test_wuffs_lzw_decode_bricks_dither() {
   CHECK_FOCUS(__func__);
   return do_test_wuffs_lzw_decode("test/data/bricks-dither.indexes.giflzw",
                                   14923, "test/data/bricks-dither.indexes",
                                   19200, UINT64_MAX, UINT64_MAX);
 }

 const char*  //
 test_wuffs_lzw_decode_bricks_nodither() {
   CHECK_FOCUS(__func__);
   return do_test_wuffs_lzw_decode("test/data/bricks-nodither.indexes.giflzw",
                                   13382, "test/data/bricks-nodither.indexes",
                                   19200, UINT64_MAX, UINT64_MAX);
 }

 const char*  //
 test_wuffs_lzw_decode_many_big_reads() {
   CHECK_FOCUS(__func__);
   return do_test_wuffs_lzw_decode("test/data/bricks-gray.indexes.giflzw", 14731,
                                   "test/data/bricks-gray.indexes", 19200,
                                   UINT64_MAX, 4096);
 }

 const char*  //
 test_wuffs_lzw_decode_many_small_writes_reads() {
   CHECK_FOCUS(__func__);
   return do_test_wuffs_lzw_decode("test/data/bricks-gray.indexes.giflzw", 14731,
                                   "test/data/bricks-gray.indexes", 19200, 41,
                                   43);
 }

 const char*  //
 test_wuffs_lzw_decode_pi() {
   CHECK_FOCUS(__func__);
   return do_test_wuffs_lzw_decode("test/data/pi.txt.giflzw", 50550,
                                   "test/data/pi.txt", 100003, UINT64_MAX,
                                   UINT64_MAX);
 }

 const char*  //
 test_wuffs_lzw_decode_output_bad() {
   CHECK_FOCUS(__func__);

   wuffs_base__io_buffer have = ((wuffs_base__io_buffer){
       .data = g_have_slice_u8,
   });
   wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
       .data = g_src_slice_u8,
   });

   // Set up src to be 20 bytes long, starting with three 8-bit literal codes
   // (0x41, 0x42, 0x43) then a bad 8-bit code 0xFF. Decoding should produce 3
   // bytes and consume 4 bytes.
   src.meta.wi = 20;
   for (int i = 0; i < src.meta.wi; i++) {
     src.data.ptr[i] = 0;
   }
   src.data.ptr[0] = 0x41;
   src.data.ptr[1] = 0x42;
   src.data.ptr[2] = 0x43;
   src.data.ptr[3] = 0xFF;

   wuffs_lzw__decoder dec;
   CHECK_STATUS("initialize",
                wuffs_lzw__decoder__initialize(
                    &dec, sizeof dec, WUFFS_VERSION,
                    WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
   wuffs_lzw__decoder__set_literal_width(&dec, 7);

   wuffs_base__status status =
       wuffs_lzw__decoder__transform_io(&dec, &have, &src, g_work_slice_u8);
   if (status.repr != wuffs_lzw__error__bad_code) {
     RETURN_FAIL("transform_io: have \"%s\", want \"%s\"", status.repr,
                 wuffs_lzw__error__bad_code);
   }

   if (have.meta.wi != 3) {
     RETURN_FAIL("have.meta.wi: have %d, want 3", (int)(have.meta.wi));
   }
   if (src.meta.ri != 4) {
     RETURN_FAIL("src.meta.ri: have %d, want 4", (int)(src.meta.ri));
   }
   return NULL;
 }

 const char*  //
 test_wuffs_lzw_decode_output_empty() {
   CHECK_FOCUS(__func__);

   wuffs_base__io_buffer have = ((wuffs_base__io_buffer){
       .data = g_have_slice_u8,
   });
   wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
       .data = g_src_slice_u8,
   });

   // Set up src to be 20 bytes long, starting with the 9-bit end code 0x101.
   // Decoding should produce 0 bytes and consume 2 bytes.
   src.meta.wi = 20;
   for (int i = 0; i < src.meta.wi; i++) {
     src.data.ptr[i] = 0;
   }
   src.data.ptr[0] = 0x01;
   src.data.ptr[1] = 0x01;

   wuffs_lzw__decoder dec;
   CHECK_STATUS("initialize",
                wuffs_lzw__decoder__initialize(
                    &dec, sizeof dec, WUFFS_VERSION,
                    WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
   wuffs_lzw__decoder__set_literal_width(&dec, 8);

   CHECK_STATUS("transform_io", wuffs_lzw__decoder__transform_io(
                                    &dec, &have, &src, g_work_slice_u8));

   if (have.meta.wi != 0) {
     RETURN_FAIL("have.meta.wi: have %d, want 0", (int)(have.meta.wi));
   }
   if (src.meta.ri != 2) {
     RETURN_FAIL("src.meta.ri: have %d, want 2", (int)(src.meta.ri));
   }
   return NULL;
 }

 const char*  //
 do_test_wuffs_lzw_decode_width(uint32_t width,
                                wuffs_base__io_buffer src,
                                wuffs_base__io_buffer want) {
   wuffs_lzw__decoder dec;
   CHECK_STATUS("initialize",
                wuffs_lzw__decoder__initialize(
                    &dec, sizeof dec, WUFFS_VERSION,
                    WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
   wuffs_lzw__decoder__set_literal_width(&dec, width);

   wuffs_base__io_buffer have = ((wuffs_base__io_buffer){
       .data = g_have_slice_u8,
   });
   CHECK_STATUS("transform_io", wuffs_lzw__decoder__transform_io(
                                    &dec, &have, &src, g_work_slice_u8));

   return check_io_buffers_equal("", &have, &want);
 }

 // A zero literal width isn't very practical: the output bytes can only be 0x00
 // and it isn't possible to encode the empty string, as the End code requires
 // two bits but the first non-Clear code after a Clear code has only one bit,
 // so it must be the literal 0x00. Nonetheless, the giflib C library accepts a
 // zero literal width (it only rejects literal widths above 8), so we do too.
 const char*  //
 test_wuffs_lzw_decode_width_0() {
   CHECK_FOCUS(__func__);

   // 0b...._...._...._...1  0x001 Clear code.
   // 0b...._...._...._..0.  0x000 Literal "0".
   // 0b...._...._...._11..  0x011 Back-ref "00"
   // 0b...._...._.100_....  0x100 Back-ref "000".
   // 0b...._..00_0..._....  0x000 Literal "0".
   // 0b...0_10.._...._....  0x010 End code.
   wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
       .data = g_src_slice_u8,
   });
   src.meta.wi = 2;
   src.data.ptr[0] = 0x4D;
   src.data.ptr[1] = 0x08;

   wuffs_base__io_buffer want = ((wuffs_base__io_buffer){
       .data = g_want_slice_u8,
   });
   want.meta.wi = 7;
   want.data.ptr[0] = 0x00;
   want.data.ptr[1] = 0x00;
   want.data.ptr[2] = 0x00;
   want.data.ptr[3] = 0x00;
   want.data.ptr[4] = 0x00;
   want.data.ptr[5] = 0x00;
   want.data.ptr[6] = 0x00;

   return do_test_wuffs_lzw_decode_width(0, src, want);
 }

 const char*  //
 test_wuffs_lzw_decode_width_1() {
   CHECK_FOCUS(__func__);

   // 0b...._...._...._..10  0x010 Clear code.
   // 0b...._...._...._00..  0x000 Literal "0".
   // 0b...._...._.001_....  0x001 Literal "1".
   // 0b...._..10_0..._....  0x100 Back-ref "01".
   // 0b...0_11.._...._....  0x011 End code.
   wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
       .data = g_src_slice_u8,
   });
   src.meta.wi = 2;
   src.data.ptr[0] = 0x12;
   src.data.ptr[1] = 0x0E;

   wuffs_base__io_buffer want = ((wuffs_base__io_buffer){
       .data = g_want_slice_u8,
   });
   want.meta.wi = 4;
   want.data.ptr[0] = 0x00;
   want.data.ptr[1] = 0x01;
   want.data.ptr[2] = 0x00;
   want.data.ptr[3] = 0x01;

   return do_test_wuffs_lzw_decode_width(1, src, want);
 }

 // ---------------- LZW Benches

 const char*  //
 do_bench_wuffs_lzw_decode(const char* filename, uint64_t iters_unscaled) {
   wuffs_base__io_buffer have = ((wuffs_base__io_buffer){
       .data = g_have_slice_u8,
   });
   wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
       .data = g_src_slice_u8,
   });

   CHECK_STRING(read_file(&src, filename));
   if (src.meta.wi <= 0) {
     RETURN_FAIL("src size: have %d, want > 0", (int)(src.meta.wi));
   }
   uint8_t literal_width = src.data.ptr[0];
   if (literal_width != 0x08) {
     RETURN_FAIL("LZW literal width: have %d, want %d", (int)(src.data.ptr[0]),
                 0x08);
   }

   bench_start();
   uint64_t n_bytes = 0;
   uint64_t iters = iters_unscaled * g_flags.iterscale;
   for (uint64_t i = 0; i < iters; i++) {
     have.meta.wi = 0;
     src.meta.ri = 1;  // Skip the literal width.
     wuffs_lzw__decoder dec;
     CHECK_STATUS("initialize",
                  wuffs_lzw__decoder__initialize(
                      &dec, sizeof dec, WUFFS_VERSION,
                      WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
     CHECK_STATUS("transform_io", wuffs_lzw__decoder__transform_io(
                                      &dec, &have, &src, g_work_slice_u8));
     n_bytes += have.meta.wi;
   }
   bench_finish(iters, n_bytes);
   return NULL;
 }

 const char*  //
 bench_wuffs_lzw_decode_20k() {
   CHECK_FOCUS(__func__);
   return do_bench_wuffs_lzw_decode("test/data/bricks-gray.indexes.giflzw", 50);
 }

 const char*  //
 bench_wuffs_lzw_decode_100k() {
   CHECK_FOCUS(__func__);
   return do_bench_wuffs_lzw_decode("test/data/pi.txt.giflzw", 10);
 }

 // ---------------- Manifest

 proc g_tests[] = {

     test_wuffs_lzw_decode_bricks_dither,
     test_wuffs_lzw_decode_bricks_nodither,
     test_wuffs_lzw_decode_interface,
     test_wuffs_lzw_decode_many_big_reads,
     test_wuffs_lzw_decode_many_small_writes_reads,
     test_wuffs_lzw_decode_output_bad,
     test_wuffs_lzw_decode_output_empty,
     test_wuffs_lzw_decode_pi,
     test_wuffs_lzw_decode_width_0,
     test_wuffs_lzw_decode_width_1,

     NULL,
 };

 proc g_benches[] = {

     bench_wuffs_lzw_decode_20k,
     bench_wuffs_lzw_decode_100k,

     NULL,
 };

 int  //
 main(int argc, char** argv) {
   g_proc_package_name = "std/lzw";
   return test_main(argc, argv, g_tests, g_benches);
 }
	// Copyright 2017 The Wuffs Authors.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// https://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	// ----------------

	/*
	This test program is typically run indirectly, by the "wuffs test" or "wuffs
	bench" commands. These commands take an optional "-mimic" flag to check that
	Wuffs' output mimics (i.e. exactly matches) other libraries' output, such as
	giflib for GIF, libpng for PNG, etc.

	To manually run this test:

	for CC in clang gcc; do
	$CC -std=c99 -Wall -Werror lzw.c && ./a.out
	rm -f a.out
	done

	Each edition should print "PASS", amongst other information, and exit(0).

	Add the "wuffs mimic cflags" (everything after the colon below) to the C
	compiler flags (after the .c file) to run the mimic tests.

	To manually run the benchmarks, replace "-Wall -Werror" with "-O3" and replace
	the first "./a.out" with "./a.out -bench". Combine these changes with the
	"wuffs mimic cflags" to run the mimic benchmarks.
	*/

	// ¿ wuffs mimic cflags: -DWUFFS_MIMIC

	// Wuffs ships as a "single file C library" or "header file library" as per
	// https://github.com/nothings/stb/blob/master/docs/stb_howto.txt
	//
	// To use that single file as a "foo.c"-like implementation, instead of a
	// "foo.h"-like header, #define WUFFS_IMPLEMENTATION before #include'ing or
	// compiling it.
	#define WUFFS_IMPLEMENTATION

	// Defining the WUFFS_CONFIG__MODULE* macros are optional, but it lets users of
	// release/c/etc.c choose which parts of Wuffs to build. That file contains the
	// entire Wuffs standard library, implementing a variety of codecs and file
	// formats. Without this macro definition, an optimizing compiler or linker may
	// very well discard Wuffs code for unused codecs, but listing the Wuffs
	// modules we use makes that process explicit. Preprocessing means that such
	// code simply isn't compiled.
	#define WUFFS_CONFIG__MODULES
	#define WUFFS_CONFIG__MODULE__BASE
	#define WUFFS_CONFIG__MODULE__LZW

	// If building this program in an environment that doesn't easily accommodate
	// relative includes, you can use the script/inline-c-relative-includes.go
	// program to generate a stand-alone C file.
	#include "../../../release/c/wuffs-unsupported-snapshot.c"
	#include "../testlib/testlib.c"

	// ---------------- LZW Tests

	const char* //
	test_wuffs_lzw_decode_interface() {
	CHECK_FOCUS(__func__);
	wuffs_lzw__decoder dec;
	CHECK_STATUS("initialize",
	wuffs_lzw__decoder__initialize(
	&dec, sizeof dec, WUFFS_VERSION,
	WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
	return do_test__wuffs_base__io_transformer(
	wuffs_lzw__decoder__upcast_as__wuffs_base__io_transformer(&dec),
	"test/data/bricks-nodither.indexes.giflzw", 1, SIZE_MAX, 19200, 0x4F);
	}

	const char* //
	do_test_wuffs_lzw_decode(const char* src_filename,
	uint64_t src_size,
	const char* want_filename,
	uint64_t want_size,
	uint64_t wlimit,
	uint64_t rlimit) {
	wuffs_base__io_buffer have = ((wuffs_base__io_buffer){
	.data = g_have_slice_u8,
	});
	wuffs_base__io_buffer want = ((wuffs_base__io_buffer){
	.data = g_want_slice_u8,
	});
	wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
	.data = g_src_slice_u8,
	});

	CHECK_STRING(read_file(&src, src_filename));
	if (src.meta.wi != src_size) {
	RETURN_FAIL("src size: have %d, want %d", (int)(src.meta.wi),
	(int)(src_size));
	}
	// The first byte in that file, the LZW literal width, should be 0x08.
	uint8_t literal_width = src.data.ptr[0];
	if (literal_width != 0x08) {
	RETURN_FAIL("LZW literal width: have %d, want %d", (int)(src.data.ptr[0]),
	0x08);
	}
	src.meta.ri++;

	CHECK_STRING(read_file(&want, want_filename));
	if (want.meta.wi != want_size) {
	RETURN_FAIL("want size: have %d, want %d", (int)(want.meta.wi),
	(int)(want_size));
	}

	wuffs_lzw__decoder dec;
	CHECK_STATUS("initialize",
	wuffs_lzw__decoder__initialize(
	&dec, sizeof dec, WUFFS_VERSION,
	WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
	wuffs_lzw__decoder__set_literal_width(&dec, literal_width);
	int num_iters = 0;
	while (true) {
	num_iters++;
	wuffs_base__io_buffer limited_have = make_limited_writer(have, wlimit);
	wuffs_base__io_buffer limited_src = make_limited_reader(src, rlimit);
	size_t old_wi = have.meta.wi;
	size_t old_ri = src.meta.ri;

	wuffs_base__status status = wuffs_lzw__decoder__transform_io(
	&dec, &limited_have, &limited_src, g_work_slice_u8);
	have.meta.wi += limited_have.meta.wi;
	src.meta.ri += limited_src.meta.ri;
	if (wuffs_base__status__is_ok(&status)) {
	if (src.meta.ri != src.meta.wi) {
	RETURN_FAIL("transform_io returned \"ok\" but src was not exhausted");
	}
	break;
	}
	if ((status.repr != wuffs_base__suspension__short_read) &&
	(status.repr != wuffs_base__suspension__short_write)) {
	RETURN_FAIL("transform_io: have \"%s\", want \"%s\" or \"%s\"",
	status.repr, wuffs_base__suspension__short_read,
	wuffs_base__suspension__short_write);
	}

	if (have.meta.wi < old_wi) {
	RETURN_FAIL("write index have.wi went backwards");
	}
	if (src.meta.ri < old_ri) {
	RETURN_FAIL("read index src.ri went backwards");
	}
	if ((have.meta.wi == old_wi) && (src.meta.ri == old_ri)) {
	RETURN_FAIL("no progress was made");
	}
	}

	if ((wlimit < UINT64_MAX) \|\| (rlimit < UINT64_MAX)) {
	if (num_iters <= 1) {
	RETURN_FAIL("num_iters: have %d, want > 1", num_iters);
	}
	} else {
	if (num_iters != 1) {
	RETURN_FAIL("num_iters: have %d, want 1", num_iters);
	}
	}

	return check_io_buffers_equal("", &have, &want);
	}

	const char* //
	test_wuffs_lzw_decode_bricks_dither() {
	CHECK_FOCUS(__func__);
	return do_test_wuffs_lzw_decode("test/data/bricks-dither.indexes.giflzw",
	14923, "test/data/bricks-dither.indexes",
	19200, UINT64_MAX, UINT64_MAX);
	}

	const char* //
	test_wuffs_lzw_decode_bricks_nodither() {
	CHECK_FOCUS(__func__);
	return do_test_wuffs_lzw_decode("test/data/bricks-nodither.indexes.giflzw",
	13382, "test/data/bricks-nodither.indexes",
	19200, UINT64_MAX, UINT64_MAX);
	}

	const char* //
	test_wuffs_lzw_decode_many_big_reads() {
	CHECK_FOCUS(__func__);
	return do_test_wuffs_lzw_decode("test/data/bricks-gray.indexes.giflzw", 14731,
	"test/data/bricks-gray.indexes", 19200,
	UINT64_MAX, 4096);
	}

	const char* //
	test_wuffs_lzw_decode_many_small_writes_reads() {
	CHECK_FOCUS(__func__);
	return do_test_wuffs_lzw_decode("test/data/bricks-gray.indexes.giflzw", 14731,
	"test/data/bricks-gray.indexes", 19200, 41,
	43);
	}

	const char* //
	test_wuffs_lzw_decode_pi() {
	CHECK_FOCUS(__func__);
	return do_test_wuffs_lzw_decode("test/data/pi.txt.giflzw", 50550,
	"test/data/pi.txt", 100003, UINT64_MAX,
	UINT64_MAX);
	}

	const char* //
	test_wuffs_lzw_decode_output_bad() {
	CHECK_FOCUS(__func__);

	wuffs_base__io_buffer have = ((wuffs_base__io_buffer){
	.data = g_have_slice_u8,
	});
	wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
	.data = g_src_slice_u8,
	});

	// Set up src to be 20 bytes long, starting with three 8-bit literal codes
	// (0x41, 0x42, 0x43) then a bad 8-bit code 0xFF. Decoding should produce 3
	// bytes and consume 4 bytes.
	src.meta.wi = 20;
	for (int i = 0; i < src.meta.wi; i++) {
	src.data.ptr[i] = 0;
	}
	src.data.ptr[0] = 0x41;
	src.data.ptr[1] = 0x42;
	src.data.ptr[2] = 0x43;
	src.data.ptr[3] = 0xFF;

	wuffs_lzw__decoder dec;
	CHECK_STATUS("initialize",
	wuffs_lzw__decoder__initialize(
	&dec, sizeof dec, WUFFS_VERSION,
	WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
	wuffs_lzw__decoder__set_literal_width(&dec, 7);

	wuffs_base__status status =
	wuffs_lzw__decoder__transform_io(&dec, &have, &src, g_work_slice_u8);
	if (status.repr != wuffs_lzw__error__bad_code) {
	RETURN_FAIL("transform_io: have \"%s\", want \"%s\"", status.repr,
	wuffs_lzw__error__bad_code);
	}

	if (have.meta.wi != 3) {
	RETURN_FAIL("have.meta.wi: have %d, want 3", (int)(have.meta.wi));
	}
	if (src.meta.ri != 4) {
	RETURN_FAIL("src.meta.ri: have %d, want 4", (int)(src.meta.ri));
	}
	return NULL;
	}

	const char* //
	test_wuffs_lzw_decode_output_empty() {
	CHECK_FOCUS(__func__);

	wuffs_base__io_buffer have = ((wuffs_base__io_buffer){
	.data = g_have_slice_u8,
	});
	wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
	.data = g_src_slice_u8,
	});

	// Set up src to be 20 bytes long, starting with the 9-bit end code 0x101.
	// Decoding should produce 0 bytes and consume 2 bytes.
	src.meta.wi = 20;
	for (int i = 0; i < src.meta.wi; i++) {
	src.data.ptr[i] = 0;
	}
	src.data.ptr[0] = 0x01;
	src.data.ptr[1] = 0x01;

	wuffs_lzw__decoder dec;
	CHECK_STATUS("initialize",
	wuffs_lzw__decoder__initialize(
	&dec, sizeof dec, WUFFS_VERSION,
	WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
	wuffs_lzw__decoder__set_literal_width(&dec, 8);

	CHECK_STATUS("transform_io", wuffs_lzw__decoder__transform_io(
	&dec, &have, &src, g_work_slice_u8));

	if (have.meta.wi != 0) {
	RETURN_FAIL("have.meta.wi: have %d, want 0", (int)(have.meta.wi));
	}
	if (src.meta.ri != 2) {
	RETURN_FAIL("src.meta.ri: have %d, want 2", (int)(src.meta.ri));
	}
	return NULL;
	}

	const char* //
	do_test_wuffs_lzw_decode_width(uint32_t width,
	wuffs_base__io_buffer src,
	wuffs_base__io_buffer want) {
	wuffs_lzw__decoder dec;
	CHECK_STATUS("initialize",
	wuffs_lzw__decoder__initialize(
	&dec, sizeof dec, WUFFS_VERSION,
	WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
	wuffs_lzw__decoder__set_literal_width(&dec, width);

	wuffs_base__io_buffer have = ((wuffs_base__io_buffer){
	.data = g_have_slice_u8,
	});
	CHECK_STATUS("transform_io", wuffs_lzw__decoder__transform_io(
	&dec, &have, &src, g_work_slice_u8));

	return check_io_buffers_equal("", &have, &want);
	}

	// A zero literal width isn't very practical: the output bytes can only be 0x00
	// and it isn't possible to encode the empty string, as the End code requires
	// two bits but the first non-Clear code after a Clear code has only one bit,
	// so it must be the literal 0x00. Nonetheless, the giflib C library accepts a
	// zero literal width (it only rejects literal widths above 8), so we do too.
	const char* //
	test_wuffs_lzw_decode_width_0() {
	CHECK_FOCUS(__func__);

	// 0b...._...._...._...1 0x001 Clear code.
	// 0b...._...._...._..0. 0x000 Literal "0".
	// 0b...._...._...._11.. 0x011 Back-ref "00"
	// 0b...._...._.100_.... 0x100 Back-ref "000".
	// 0b...._..00_0..._.... 0x000 Literal "0".
	// 0b...0_10.._...._.... 0x010 End code.
	wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
	.data = g_src_slice_u8,
	});
	src.meta.wi = 2;
	src.data.ptr[0] = 0x4D;
	src.data.ptr[1] = 0x08;

	wuffs_base__io_buffer want = ((wuffs_base__io_buffer){
	.data = g_want_slice_u8,
	});
	want.meta.wi = 7;
	want.data.ptr[0] = 0x00;
	want.data.ptr[1] = 0x00;
	want.data.ptr[2] = 0x00;
	want.data.ptr[3] = 0x00;
	want.data.ptr[4] = 0x00;
	want.data.ptr[5] = 0x00;
	want.data.ptr[6] = 0x00;

	return do_test_wuffs_lzw_decode_width(0, src, want);
	}

	const char* //
	test_wuffs_lzw_decode_width_1() {
	CHECK_FOCUS(__func__);

	// 0b...._...._...._..10 0x010 Clear code.
	// 0b...._...._...._00.. 0x000 Literal "0".
	// 0b...._...._.001_.... 0x001 Literal "1".
	// 0b...._..10_0..._.... 0x100 Back-ref "01".
	// 0b...0_11.._...._.... 0x011 End code.
	wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
	.data = g_src_slice_u8,
	});
	src.meta.wi = 2;
	src.data.ptr[0] = 0x12;
	src.data.ptr[1] = 0x0E;

	wuffs_base__io_buffer want = ((wuffs_base__io_buffer){
	.data = g_want_slice_u8,
	});
	want.meta.wi = 4;
	want.data.ptr[0] = 0x00;
	want.data.ptr[1] = 0x01;
	want.data.ptr[2] = 0x00;
	want.data.ptr[3] = 0x01;

	return do_test_wuffs_lzw_decode_width(1, src, want);
	}

	// ---------------- LZW Benches

	const char* //
	do_bench_wuffs_lzw_decode(const char* filename, uint64_t iters_unscaled) {
	wuffs_base__io_buffer have = ((wuffs_base__io_buffer){
	.data = g_have_slice_u8,
	});
	wuffs_base__io_buffer src = ((wuffs_base__io_buffer){
	.data = g_src_slice_u8,
	});

	CHECK_STRING(read_file(&src, filename));
	if (src.meta.wi <= 0) {
	RETURN_FAIL("src size: have %d, want > 0", (int)(src.meta.wi));
	}
	uint8_t literal_width = src.data.ptr[0];
	if (literal_width != 0x08) {
	RETURN_FAIL("LZW literal width: have %d, want %d", (int)(src.data.ptr[0]),
	0x08);
	}

	bench_start();
	uint64_t n_bytes = 0;
	uint64_t iters = iters_unscaled * g_flags.iterscale;
	for (uint64_t i = 0; i < iters; i++) {
	have.meta.wi = 0;
	src.meta.ri = 1; // Skip the literal width.
	wuffs_lzw__decoder dec;
	CHECK_STATUS("initialize",
	wuffs_lzw__decoder__initialize(
	&dec, sizeof dec, WUFFS_VERSION,
	WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED));
	CHECK_STATUS("transform_io", wuffs_lzw__decoder__transform_io(
	&dec, &have, &src, g_work_slice_u8));
	n_bytes += have.meta.wi;
	}
	bench_finish(iters, n_bytes);
	return NULL;
	}

	const char* //
	bench_wuffs_lzw_decode_20k() {
	CHECK_FOCUS(__func__);
	return do_bench_wuffs_lzw_decode("test/data/bricks-gray.indexes.giflzw", 50);
	}

	const char* //
	bench_wuffs_lzw_decode_100k() {
	CHECK_FOCUS(__func__);
	return do_bench_wuffs_lzw_decode("test/data/pi.txt.giflzw", 10);
	}

	// ---------------- Manifest

	proc g_tests[] = {

	test_wuffs_lzw_decode_bricks_dither,
	test_wuffs_lzw_decode_bricks_nodither,
	test_wuffs_lzw_decode_interface,
	test_wuffs_lzw_decode_many_big_reads,
	test_wuffs_lzw_decode_many_small_writes_reads,
	test_wuffs_lzw_decode_output_bad,
	test_wuffs_lzw_decode_output_empty,
	test_wuffs_lzw_decode_pi,
	test_wuffs_lzw_decode_width_0,
	test_wuffs_lzw_decode_width_1,

	NULL,
	};

	proc g_benches[] = {

	bench_wuffs_lzw_decode_20k,
	bench_wuffs_lzw_decode_100k,

	NULL,
	};

	int //
	main(int argc, char** argv) {
	g_proc_package_name = "std/lzw";
	return test_main(argc, argv, g_tests, g_benches);
	}